Method and apparatus for forming a hard disk drive base plate with an extended height

ABSTRACT

A method for forming a hard disk drive base plate with an extended height is described. The method may include forming an initial hard disk drive base plate, forming a filler shim, and forming a shroud. The method may also include joining the initial hard disk drive base plate, the filler shim, and the shroud to extend a height of walls of the formed initial hard disk drive base plate, and to form the hard disk drive base plate with the extended height.

FIELD

Embodiments of the present invention relate generally to the field ofmanufacturing metal parts and more specifically, a manufacturing processfor forming a hard disk drive base plate with an extended height.

BACKGROUND

The housing of a hard disk drive for use in computer systems typicallyincludes a cover and a base plate attached with screws. A base platesupports the hard disk drive assembly (e.g., spindle, motor, andactuator).

One conventional base plate manufacturing process includes press workinga sheet of metal with side frames mounted on opposing sides. In thisprocess, a base plate is press worked to form a concave portion with afew holes for motor mounting. Two side frames are press worked fromsheet metal and are fixedly mounted on the opposite sides of the baseplate.

When a base plate is formed by a forging process performed on a blank,the height of the side walls is limited. The forging process appliesplastic deformation on the original blank, such that the resultantformed hard disk drive base plate shape is irreversibly formed. Due,however, to the limitations of plastic deformation and the chosen blankmaterial, the wall height of the walls of the formed hard disk drivebase plate are not sufficient to house a finished hard disk drive,including the spindle, motor, actuator, and other parts of a hard diskdrive assembly.

SUMMARY

A method for forming a hard disk drive base plate with an extendedheight is described. An initial hard disk drive base plate, a fillershim, and a shroud are formed. The initial hard disk drive base plate,the filler shim, and the shroud are joined to extend a height of wallsof the formed initial hard disk drive base plate, and to form the harddisk drive base plate with the extended height.

A production system for forming a hard disk drive base plate with anextended height is also described. A first stage of the productionsystem is used to advance a blank cut from an extruded sheet throughmultiple stations of a transfer die assembly to form an initial harddisk drive base plate. A second stage of the production system is usedto punch a filler shim from a sheet of metal. A third stage of theproduction system is used to form a shroud. Finally, a fourth stage ofthe production system is used to join the initial hard disk drive baseplate, the filler shim, and the shroud to extend a height of walls ofthe formed initial hard disk drive base plate and to form the hard diskdrive base plate with the extended height.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are illustrated by way of example,and not limitation, in the figures of the accompanying drawings inwhich:

FIG. 1 illustrates a joined hard disk drive base plate with an extendedheight;

FIG. 2A provides another illustration of the joined extended height harddisk drive base plate with a reference to a cross section location:

FIG. 2B illustrates the cross section of the joined hard disk drive baseplate referenced in FIG. 2A;

FIG. 3 provides an exploded view of the component parts of an extendedheight hard disk drive base plate;

FIG. 4 illustrates welding paths for joining the hard disk drive baseplate, shroud, and filler shim to form the hard disk drive base platewith an extended height;

FIG. 5A illustrates a block diagram of a method of forming a fillershim;

FIG. 5B illustrates the formation of a filler shim from the stamping ofa sheet of metal;

FIG. 6 illustrates a block diagram of a method of forming a hard diskdrive base plate;

FIG. 7A illustrates a block diagram of a method of forming a shroud;

FIG. 7B illustrates an extruded hollow bar for forming a shroud;

FIG. 7C illustrates a formed shroud; and

FIG. 8 illustrates a block diagram of a method for joining the formedhard disk drive base plate, shroud, and filler ship to form the harddisk drive base plate with an extended height.

DETAILED DESCRIPTION

A method using a formed hard disk drive base plate, a shroud, and afiller shim to form a hard disk drive base plate with an extended heightis described. For one embodiment, an initial blank base plate isadvanced through a plurality of stations of a transfer die assembly toform and forge a hard disk drive base plate. A shroud to extend theheight of the formed and forged hard disk drive base plate is alsoformed. For one embodiment, the forming of the shroud may includeforging the shroud through a plurality of stations, similar the formingof the hard disk drive base plate. For another embodiment, the formingof the shroud may also be performed by generating a hollow bar through ametal extrusion process, and cutting sections from the hollow bar with asaw to obtain shrouds of a desired height. For one embodiment, a fillershim is also created by stamping a thin metal sheet. In the embodimentsdiscussed below, the hard disk drive base plate, filler shim, and shroudare joined. For example, the hard disk drive base plate may be welded tothe shroud with the filler shim disposed therebetween. The weldingtogether of the hard disk drive base plate, filler shim, and shroudforms the extended height hard disk drive base plate, which may then beutilized in the assembly of a hard disk drive.

Below is a discussion of the component parts, their relationship withone another, and the finished extended height hard disk drive baseplate. The processes for forming the component parts are then described.Finally, the process for welding and finishing the extended height harddisk drive base plate is described.

FIG. 1 illustrates a joined hard disk drive base plate 100 with anextended height. The extended height hard disk drive base plate withformed parts 110, as discussed in greater detail below, is formed byjoining hard disk drive base plate 102, filler shim 106, and shroud 104.FIG. 2A provides another illustration of the joined extended height harddisk drive base plate 200 with a reference to a cross section locationL-L. FIG. 2B illustrates cross section L-L of the base plate 202, fillershim 206, and hroud 204 of the joined hard disk drive base plate 250illustrated in FIG. 2A.

FIG. 3 provides an exploded view 300 of the component parts of anextended height hard disk drive base plate. The view illustrated in FIG.3 shows additional details of the base plate 102, shroud 104, and fillershim 106 illustrated in FIG. 1. In FIG. 3, the component parts of theextended height hard disk drive base plate include hard disk drive baseplate 302, filler shim 306, and shroud 304.

A hard disk drive base plate 302 with formed parts (e.g., motor hub,actuator pivot bearing post, etc.) for supporting a hard disk driveassembly (e.g., spindle, motor, actuator, etc.) is illustrated in FIG.3. In one embodiment, the base plate 302 may be formed by forging a baseplate from an initial base plate, cut for an extruded sheet of blankmaterial. The base plate 302 may be forged in a single forging operationperformed on the initial base plate. The base plate 302 may also beforged with a sequence of progressive forging operations. A progressivedie assembly, including multiple stations, may be used to perform thesequence of progressive forging operations by advancing the hard diskdrive base plate from station to station to complete each of a pluralityof progressive forgings. The specific forging operations at thedifferent stages form, either partially or fully, parts on the hard diskdrive base plate as it is advanced through the sequence of stages.Furthermore, the sequence of progressive forgings form, either partiallyor fully, specific parts on the hard disk drive base plate at specificstages in order to manage the movement of material caused by the forgingoperations, and to ensure a uniform thickness of the resulting fullyformed hard disk drive base plate, such as base plate 302. Furthermore,the order of forging operations and formation of different parts ensuresthat the intricate details of the hard disk drive base plate areproperly formed.

In another embodiment, the base plate may be formed using a conventionalhard disk drive base plate forming technique, such as, press working asheet of metal to form a base plate, press working a sheet of metal toform a side walls, and assembling the base plate and side walls to formthe hard disk drive base plate.

The metal used for forming the hard disk drive base plate may be chosenbased on various factors—for example, design requirements, desiredmaterial properties, reduced contamination (i.e., silicon, copper, zinc,etc. contamination) of the raw material for the hard disk drive baseplate, and reduced natural magnetism of the hard disk drive base plate.In one embodiment, the hard disk drive base plate 302 is formed fromaluminum alloy AL 6061. However, other aluminum alloys, such as AL 5052,AL 110, etc. may be used. Furthermore, due to design requirements,desired material properties, or other considerations, a 1000 seriesaluminum alloy may be selected for forming the component parts of theextended height hard disk drive base plate when a higher aluminum puritycontent, as compared to AL6061, is desired. When an AL1000 series alloyis chosen due to design considerations, each of the hard disk drive baseplate 302, shroud 304, and filler shim 306 are formed from the selectedsame AL1000 series alloy. For alternative embodiments, however, othersuitable materials such as, for example, cold rolled or low carbon steelmay also be used.

FIG. 3 further illustrates a shroud 304 for extending the height of thewalls of the hard disk drive base plate 302. In one embodiment, theshroud 304 is also formed from an aluminum alloy, such as AL6061.Furthermore, the aluminum alloy used to form the shroud 304 is selectedto be the same alloy used to form the hard disk drive base plate 302.

When forming the shroud, shroud 304 is shaped such that a marryingsurface 314 of the shroud corresponds to the shape of a marrying surface312 of the hard disk drive base plate 302, as well as the marryingsurfaces 316 of the filler shim. The marrying surfaces (e.g., surfaces312, 314, and 316), as discussed herein, are the surfaces of the harddisk drive base plate 302, shim 306, and shroud 304 that are pressedtogether when the extended height hard disk drive base plate is formed.In one embodiment, the shroud 304 may also be formed by performing oneor more forging operations using the techniques discussed above. Theshroud 304 is formed by the one or more forging operations with a shapeof a marrying surface 314 that corresponds to the marrying surface 312of the top of the hard disk base plate walls, and with a requiredheight, as discussed below.

In another embodiment, the shroud 304 may be formed using a metalextrusion process to form an extruded hollow bar 720, as illustrated inFIG. 7B. The extrusion process forms the hollow bar 720 with across-sectional shape 722 that corresponds to a shape of the marryingsurface 312 of the hard disk drive base plate 302 walls. A section 724of the extruded hollow bar 720 may then be cut from the length of thehollow bar to obtain shroud 304 with the required height. A plurality ofsections may be cut from the extruded hollow bar 720 to obtain aplurality of shrouds with the required height. In one embodiment,sections of varying heights may be cut from the extruded hollow bar toobtain shrouds of varying heights based on design considerations ofresulting joined hard disk drive base plates.

Returning to FIG. 3, the height of the formed shroud 304 may be selectedbased on design considerations, such as a required height of a formedhard disk drive base plate's walls for accommodating assembled hard diskdrive components, as well as other factors. In one embodiment, thecombined heights of the walls of the hard disk drive base plate 302,shroud 304, and the filler shim 306 result in a total height, where thetotal height is the height required for a specific use or designrequirement of the joined hard disk drive base plate (e.g., hard diskdrive base plate 100 illustrated in FIG. 1). The relative heights of thewalls of the hard disk drive base plate 302, shroud 304 and filler shim306 may be given according to the formula,H_(total)=H_(base plate)+H_(shroud)+H_(shim), such that the relativebase plate 302, shroud 304, and filler shim 306 heights can be adjustedso long as the sum of their heights equals the total height, H_(total).In one embodiment, H_(total) is greater than 15 millimeters.

The filler shim 306, illustrated in FIG. 3, is a thin strip of metal.The filler shim 306 may be formed from a stamping process applied to ametal sheet, as will be discussed in greater detail below in FIGS. 5Aand 5B. A shape of the marrying surfaces 316 of the stamped filler shim306 correspond to the shape of the marrying surface 314 of the shroud304 and the marrying surface 312 of the hard disk drive base plate 302.Furthermore, the metal sheet may have a thickness in the range of 0.3 to0.8 millimeters resulting in a filler shim with H_(shim) in thatthickness range.

The filler shim 306 is to be disposed in between the hard disk drivebase plate 302 and the shroud 304 during a welding process that joinsthe marrying surfaces of the hard disk drive base plate 302, shroud 304,and filler shim 306. As illustrated in FIG. 4, the hard disk drive baseplate 302, filler shim 306, and shroud 304 are joined by performing awelding process along exterior 410 and interior 420 welding paths of theextended height hard disk drive base plate 400. The interior andexterior welding may be performed on the extended height hard disk drivebase plate in any order (i.e., interior 420 then exterior 410, orexterior 410 then interior 420), as well as simultaneously, and in anydirection. The welding process may utilize different welding techniques,such as plasma welding, laser welding, tungsten inert gas (TIG) welding,gas tungsten arc welding (GTAW), as well as other welding techniques,when joining the hard disk drive base plate 302, shroud 304, and fillershim 306

In embodiments, the stamped filler shim 306 may be formed from AL4047,AL 4043, or other 4000 series aluminum alloy. The 4000 series aluminumalloy is utilized to achieve proper fusion during the welding processwhen forming the extended height hard disk drive base plate.Furthermore, use of the 4000 series aluminum alloy, when joining anAL6061 base plate and an AL6061 shroud, assists in the prevention ofthermal shock and hot cracking during the welding process.

The forming of the component parts (e.g., the hard disk drive base plate302, shroud 304, and filler shim 306) discussed above in FIGS. 1-3 maybe performed in any order, and at different or the same times. Thus, theprocesses illustrated and discussed below in FIG. 5A, FIG. 6, and FIG.7A need not be performed in any particular order, so long as eachcomponent part has been formed prior to the joining process discussedbelow in FIG. 8.

FIG. 5A illustrates a block diagram of a method 500 of forming a fillershim. In one embodiment, filler shim 556 of FIG. 5B may be formed fromthe stamping process of FIG. 5A. A filler shim 556 is stamped from athin sheet of metal 552 (block 502). The sheet of metal 552 may be analuminum alloy, such as AL4047, having a thickness in the range of 0.3to 0.8 millimeters. As discussed herein, one or more stamps (not shown),may be utilized by machine or stamping presses to produce the desiredform of the stamped filler shim 556. A first press or punch operationmay be utilized to form a desired inner shape of filler shim by removingthe material from the sheet of metal 552, as illustrated with partiallyformed filler shim 554. A second press or punch operation may then beperformed to form a desired outer shape of the filler shim by removing afiller shim, such as filler shim 556, from the sheet of metal 552.

The stamped filler shims, such as filler shim 556, are then cleaned(block 504). During the stamping performed above in block 502, grease,residue, or other forms of contamination may accumulate on the stampedfiller shims. Thus, one or more cleaning processes, such as solventcleaning, alkaline detergent cleaning, etc. may be used to clean thestamped filler shims. Furthermore, the selected cleaning process(es) maybe performed along a conveyor system, where the stamped filler shims arewashed while traveling along a conveyor belt. The cleaning process(es)could also, or alternatively, include a rack and basket type system,where filler shims are put into racks or baskets and lowered intocleaning tanks along a conveyor line. Other cleaning processes may beused consistent with the discussion herein.

FIG. 6 illustrates a block diagram of a method 600 of forming a harddisk drive base plate. In one embodiment, the hard disk drive base plateis forged (block 602). As discussed above, an initial blank base platemay be advanced through a plurality of stations of a transfer dieassembly. Parts are forged on the initial blank base plate to form ahard disk drive base plate (e.g., base plate 102 in FIG. 1 or base plate302 in FIG. 3). The forging can include forming various parts of thehard disk drive base plate, such as a motor hub, a voice coil motorrelief surface, and an actuator pivot bearing post. Other parts are alsoforged from the initial blank to form the final hard disk drive baseplate form. The forging may occur over a sequence of stages, where eachstage in the sequence involves forming, either partially or fully,various features of the hard disk drive base plate. Furthermore, theprogressive forging may also be used for forming a shroud (e.g., shroud104 in FIG. 1 or shroud 304 in FIG. 3).

Machining is then performed on the marrying surface of the formed harddisk drive base plate (block 604). In one embodiment, the machining,such as computer numerical controlled (CNC) machining, is performed onthe surface 312 of the formed hard disk drive base plate 302 that willbe in contact with the stamped filler shim 306 during welding. In oneembodiment, the machining refines the shape of the marrying surface,ensures surface evenness, etc. prior to the joining process discussedbelow in FIG. 8.

The hard disk drive base plate is then cleaned (block 606). As discussedabove, residual dirt and/or oil may be deposited on the base plateduring the forming and/or machining processes of blocks 606. Thus,cleaning processes similar to those employed in block 504 of FIG. 5 maybe performed on the formed and machined hard disk drive base plate.

FIG. 7A illustrates a block diagram of a method 700 of forming a shroud.As discussed herein, the shroud is utilized to extend the height of thewalls of a formed hard disk drive base plate.

The process begins by forming the shroud (block 702). In one embodiment,a formed shroud (e.g., shroud 740 illustrated in FIG. 7C) may be formedthrough a series of one or more forgings, as discussed herein. Inanother embodiment, the formed shroud 740 is formed by cutting a section724 from an extruded hollow bar 720, as illustrated in FIG. 7B. In thisembodiment, the cut section 724 forms shroud 740. As discussed herein,the extruded hollow bar has a cross-sectional shape 722 that correspondsto the shape of the marrying surface 316 of the stamped filler shim 306as formed in FIG. 5A, which in turn corresponds to the marrying surface312 of the hard disk drive base plate 302 as formed in FIG. 6.Furthermore, the section 724 cut from the extruded hollow bar 720 mayhave a thickness that ensures the extended wall height the joined harddisk drive base plate (i.e., the finished welded base plate, shim, andshroud) exceeds 15 millimeters and/or a height defined by designrequirements.

Machining is then performed on the marrying surface of the formed shroud(block 704). The machining, such as CNC machining, is utilized to refinethe shape, ensure surface evenness, etc. of the marrying surface 314 ofthe shroud (e.g., shroud 308 or shroud 740 formed at block 702), aspreparation for the joining process discussed below in FIG. 8.

The formed and machined shroud is then cleaned (block 706), as discussedherein.

After the component parts have each been formed, machined, and cleaned,the parts may then be joined to form the extended height hard disk drivebase plate. FIG. 8 illustrates a block diagram of a method 800 forjoining a hard disk drive base plate, shroud, and filler shim to formthe hard disk drive base plate with an extended height. For example, theprocess discussed below in FIG. 8 can be used to form the extendedheight hard disk drive base plate 100 illustrated in FIG. 1.

The process begins by pre-heating the component parts prior to welding(block 802). In one embodiment, the component parts comprise the formedhard disk drive base plate, the formed shroud, and the stamped fillershim. The pre-heating of the component parts is performed as part ofstress relief and preparation of the component parts for welding. Thatis, during welding and without pre-heating, the temperature of thecomponent parts will be raised dramatically, leading to potentialthermal shock, thermal cracking, material distortion, and other unwantedside effects. By pre-heating the component parts in block 802, theeffects of thermal shock, thermal cracking, material distortion, etc.are reduced and/or eliminated, thereby ensuring better fusion andre-alloying of the component parts during welding.

After pre-heating, the component parts are arranged to align themarrying surfaces of the hard disk drive base plate, filler shim, andshroud (block 804). As illustrated in FIG. 3, marrying surface 312 ofhard disk drive base plate 302 is aligned with a first marrying surface316 of the filler shim 306. Similarly, a second marrying surface 316 ofthe filler shim 306 is aligned with marrying surface 314 of shroud 304.

After the marrying surfaces are aligned, welding is performed along aninterior welding path and an exterior welding path of the arrangedcomponent parts to form the extended height hard disk drive base plate(block 806). As discussed herein, the welding processes performed atblock 808 may be a plasma, laser, TIG, GRAW or other welding process.Furthermore, the welding along the interior welding path and the weldingalong the exterior welding path may be performed in either order (i.e.,inner then outer, or outer than inner), as well as simultaneously. Oncethe welding is complete, an unfinished version of the extended heighthard disk drive base plate has been formed.

Post-welding stress relief is then performed (block 808). Post weldingstress relief can involve gradually lowering the temperature of theformed, but unfinished, extended height hard disk drive base plate. Thegradual lowering of the formed extended height hard disk drive baseplate again prevents against thermal shock, thermal cracking, materialdistortion, etc. as discussed above.

In one embodiment, heating and cooling conveyor systems or heating andcooling chambers may be utilized for pre-welding stress relief andpost-welding stress relief, as discussed in blocks 802 and 808.Furthermore, a robot or other mechanized means may be employed toperform the component part arrangement and welding discussed in blocks804 and 806, as well as to remove the pre-heated component parts fromthe heating conveyor or chamber, and to place the welded extended heighthard disk drive base plate on the cooling chamber or on the coolingconveyor system.

A first set of post-weld machining processes are performed to refine theshape of the extended height hard disk drive base plate (block 810). CNCbased machining may be performed of the base plate surfaces and/or wallsof the extended height hard disk drive base plate to obtain the shapesand features of the extended height hard disk drive base plate. Once themachining is complete, the extended height hard disk drive base plate iscleaned and plated (block 812). As discussed herein, due to machiningoperations, as well as the welding, grease, residue, or othercontaminants may gather on the extended height hard disk drive baseplate. A cleaning process, as discussed herein, is therefore applied tothe extended height hard disk drive. Once cleaned, an E-coating,EN-plating, Bimetal Black EN plating may be applied to the hard diskdrive base plate to help prevent against corrosion of the hard diskdrive base plate.

A second set of post-weld machining processes are performed aftercleaning and plating process to further refine critical areas of theextended height hard disk drive base plate (block 814). The post-weldingmachining processes include, for example, performing CNC machining torefine datums, a motor hub area, an actuator pole, actuator sittingareas, a VCM sitting area, blind holes, and thread forming in blindholes of the extended height hard disk drive base plate.

A second cleaning of the extended height hard disk drive base plate isperformed after the second machining (block 816), utilizing one or moreof the cleaning techniques discussed herein. After the second cleaning,the extended height HDD base plate is ready for packaging, shipment,assembly of a hard disk drive, etc.

Each of the blocks illustrated in FIGS. 5A, 6, 7A, and 8, as describedabove, may be accomplished in different stages of a system for producinghard disk drive base plates with extended heights. The stages may beperformed sequentially, in parallel, partially in parallel, partiallysequentially, etc. For example, a stage in the production system mayinvolve pre-heating each of the component parts in parallel, anotherstage in production system may involve sequentially aligning an initialhard disk drive base plate, with a filler shim, and then aligning thosewith a shroud, and yet another stage may include joining the initialbase plate, filler shim, and shroud through a welding process.Additional stages may be used for forming finished hard disk drive baseplates with an extended height in accordance with the discussion andillustrations set forth herein.

In the foregoing specification, the invention has been described inreference to specific exemplary embodiments thereof. It will, however,be evident that various modifications and changes may be made theretowithout departing from the described spirit and scope of the invention.The specification and drawings are, accordingly, to be regarded asillustrative rather than a restrictive sense.

1-14. (canceled)
 15. A production system for forming a hard disk drivebase plate with an extended height, comprising: a first stage of theproduction system to advance a blank cut from an extruded sheet throughmultiple stations of a transfer die assembly to forge and form aninitial hard disk drive base plate; a second stage of the productionsystem to punch a filler shim from a sheet of metal; a third stage ofthe production system to form a shroud; and a fourth stage of theproduction system to join the initial hard disk drive base plate, thefiller shim, and the shroud to extend a height of walls of the formedinitial hard disk drive base plate and to form the hard disk drive baseplate with the extended height.
 16. The production system of claim 15,wherein the third stage of the production system further comprises ametal extruder to form a hollow bar with a cross-sectional shape thatcorresponds to a shape of a marrying surface of walls of the initialhard disk drive base plate, and a saw to cut a section from the hollowbar to form the shroud.
 17. The production system of claim 15, whereinthe third stage of the production system performs a sequence of forgingson an initial blank to form the shroud.
 18. The production system ofclaim 15, further comprising: a welding stage to join the initial harddisk drive base plate, the filler shim, and the shroud, the weldingstage to align a marrying surface of the initial hard disk drive baseplate with a first marrying surface of the filler shim, align a marryingsurface of the shroud with a second marrying surface of the filler shim,and weld along an interior path and an exterior path of the alignedinitial hard disk drive base plate, filler shim, and shroud.
 19. Theproduction system of claim 15, further comprising: a first cleaningstage to clean the formed hard disk drive base plate with the extendedheight, a surface treatment stage to apply a surface treatment to thecleaned hard disk drive base plate with the extended height, wherein theapplied surface treatment is one of an Electroless Nickel plating,Electro-coating, or Bimetal Black Electroless Nickel plating, amachining stage to perform one or more machining operations on thesurface treated and cleaned hard disk drive base plate with the extendedheight to refine one or more parts of the surface treated and cleanedhard disk drive base plate with the extended height, and a secondcleaning stage to clean the machined hard disk drive base plate with theextended height to produce a finished hard disk drive base plate with anextended height.
 20. The production system of claim 15, wherein theinitial hard disk drive base plate and the shroud are formed fromaluminum 6061, and the filler shim is formed from aluminum 4047.